Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs

Lewisuchus admixtus is an enigmatic early dinosauriform from the Chañares Formation, Ladinian of Argentina, which has been recently considered a member of Silesauridae. Yet, it differs markedly from Late Triassic silesaurids in dental and vertebral anatomy. Indeed, a detailed redescription of its ho...

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Autores principales: Bittencourt, J.S., Arcucci, A.B., Marsicano, C.A., Langer, M.C.
Formato: JOUR
Materias:
basal dinosauromorphs
Lewisuchus
Middle Triassic
Pseudolagosuchus
silesaurids
Dinosauria
Dinosauromorpha
Otus
Proterochampsidae
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_14772019_v13_n3_p189_Bittencourt
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_14772019_v13_n3_p189_Bittencourt
record_format dspace
spelling todo:paper_14772019_v13_n3_p189_Bittencourt2023-10-03T16:19:09Z Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs Bittencourt, J.S. Arcucci, A.B. Marsicano, C.A. Langer, M.C. basal dinosauromorphs Lewisuchus Middle Triassic Pseudolagosuchus silesaurids Dinosauria Dinosauromorpha Otus Proterochampsidae Lewisuchus admixtus is an enigmatic early dinosauriform from the Chañares Formation, Ladinian of Argentina, which has been recently considered a member of Silesauridae. Yet, it differs markedly from Late Triassic silesaurids in dental and vertebral anatomy. Indeed, a detailed redescription of its holotype allowed the identification of several features of the skeleton previously unrecognized amongst silesaurids. These include pterygoid teeth, a dorsomedial posttemporal opening on the otoccipital, foramina associated with cranial nerves X-XII on the caudal region of the prootic-otoccipital, and postaxial neck/trunk vertebrae with craniocaudally expanded neural spines. The presence of a single row of presacral scutes was also confirmed. Some elements previously referred to, or found associated with, the holotype, including a lower jaw, pedal elements and an astragalus, more probably correspond to proterochampsid remains. The anatomical information available for the holotype of L. admixtus was rescored into a new phylogenetic dataset for dinosauromorphs, mostly based on previous works. Lewisuchus admixtus and Pseudolagosuchus major are treated as distinct OTUs because their preserved skeletons mostly lack overlapping parts. The parsimony analysis supports the basal position of L. admixtus within dinosauriforms, prior to the silesaurid-dinosaur split, rather than at the base of Silesauridae. This suggests that a higher number of early dinosauriform clades branched in the Middle and Late Triassic than previously suggested. © 2014 © 2014 The Trustees of the Natural History Museum, London 2014. All Rights Reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_14772019_v13_n3_p189_Bittencourt
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic basal dinosauromorphs
Lewisuchus
Middle Triassic
Pseudolagosuchus
silesaurids
Dinosauria
Dinosauromorpha
Otus
Proterochampsidae
spellingShingle basal dinosauromorphs
Lewisuchus
Middle Triassic
Pseudolagosuchus
silesaurids
Dinosauria
Dinosauromorpha
Otus
Proterochampsidae
Bittencourt, J.S.
Arcucci, A.B.
Marsicano, C.A.
Langer, M.C.
Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
topic_facet basal dinosauromorphs
Lewisuchus
Middle Triassic
Pseudolagosuchus
silesaurids
Dinosauria
Dinosauromorpha
Otus
Proterochampsidae
description Lewisuchus admixtus is an enigmatic early dinosauriform from the Chañares Formation, Ladinian of Argentina, which has been recently considered a member of Silesauridae. Yet, it differs markedly from Late Triassic silesaurids in dental and vertebral anatomy. Indeed, a detailed redescription of its holotype allowed the identification of several features of the skeleton previously unrecognized amongst silesaurids. These include pterygoid teeth, a dorsomedial posttemporal opening on the otoccipital, foramina associated with cranial nerves X-XII on the caudal region of the prootic-otoccipital, and postaxial neck/trunk vertebrae with craniocaudally expanded neural spines. The presence of a single row of presacral scutes was also confirmed. Some elements previously referred to, or found associated with, the holotype, including a lower jaw, pedal elements and an astragalus, more probably correspond to proterochampsid remains. The anatomical information available for the holotype of L. admixtus was rescored into a new phylogenetic dataset for dinosauromorphs, mostly based on previous works. Lewisuchus admixtus and Pseudolagosuchus major are treated as distinct OTUs because their preserved skeletons mostly lack overlapping parts. The parsimony analysis supports the basal position of L. admixtus within dinosauriforms, prior to the silesaurid-dinosaur split, rather than at the base of Silesauridae. This suggests that a higher number of early dinosauriform clades branched in the Middle and Late Triassic than previously suggested. © 2014 © 2014 The Trustees of the Natural History Museum, London 2014. All Rights Reserved.
format JOUR
author Bittencourt, J.S.
Arcucci, A.B.
Marsicano, C.A.
Langer, M.C.
author_facet Bittencourt, J.S.
Arcucci, A.B.
Marsicano, C.A.
Langer, M.C.
author_sort Bittencourt, J.S.
title Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
title_short Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
title_full Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
title_fullStr Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
title_full_unstemmed Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs
title_sort osteology of the middle triassic archosaur lewisuchus admixtus romer (chañares formation, argentina), its inclusivity, and relationships amongst early dinosauromorphs
url http://hdl.handle.net/20.500.12110/paper_14772019_v13_n3_p189_Bittencourt
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